Derivative Financial Instruments (Schedule of Company's Derivative Instruments on Other Comprehensive Income and the Consolidated Statement of Operations) (Details) - Foreign currency forward contracts - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recognized in OCI - Effective Portion	$ 534	$ 1,084	$ 863	$ 450
Gains (Losses) Reclassified from OCI into Income - Effective Portion	536	960	842	(366)
Net revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) Reclassified from OCI into Income - Effective Portion	672	1,187	1,086	(515)
Cost of revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) Reclassified from OCI into Income - Effective Portion	(6)	(7)	(8)	(1)
Research and development
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) Reclassified from OCI into Income - Effective Portion	(20)	(13)	(46)	86
Sales and marketing
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) Reclassified from OCI into Income - Effective Portion	(98)	(157)	(167)	73
General and administrative
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) Reclassified from OCI into Income - Effective Portion	$ (12)	$ (50)	$ (23)	$ (9)